Fatigue Life Reduction of Roller Bearings Due to Debris Denting: Part II - Experimental Validation

Abstract

Life tests have been conducted for tapered roller bearings. Bearing race ways are pre-dented with particles of various types and sizes. Life reductions due to surface indentation are calculated by a stress-based life model using the measured raceway topography. The predictions are compared and validated with testing results. The study concludes that bearing life reduction is primarily determined by the slopes and area densities of surface indentations. Life reduction factor decreases as dent slope and area-density increase. The hardness and fracture toughness of the denting particles have a noticeable effect on bearing life reduction. Ductile particles cause more severe life reduction than the brittle particles. Surface failures associated with small dents are superficial and often appear in forms of “micro-pitting” and “micro-peeling.” Large dents generated by ductile particles cause severe damage to bearing raceways and are more likely to induce surface pits and spalls. Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999